Linux/CMake: INTERFACE_INCLUDE_DIRECTORIES property of target hidapi::hidapi not correctly set in libhidapi.cmake (v0.12.0)

[stsichler]

I have built hidapi (0.12.0) from source and installed it into a local directory (/home/xxxx/.lib/hidapi-0.12.0/x86_64-linux-gnu) using following commands:

git clone https://github.com/libusb/hidapi.git --branch hidapi-0.12.0 --depth 1 -c advice.detachedHead=false .lib/hidapi-0.12.0/src
cmake -S .lib/hidapi-0.12.0/src -B .lib/hidapi-0.12.0/x86_64-linux-gnu/.build -DCMAKE_INSTALL_PREFIX=.lib/hidapi-0.12.0/x86_64-linux-gnu -DBUILD_SHARED_LIBS=OFF
cmake --build .lib/hidapi-0.12.0/x86_64-linux-gnu/.build --config Release
cmake --install .lib/hidapi-0.12.0/x86_64-linux-gnu/.build

hidapi properly installes into the correct location, but the resulting contents of the generated libhidapi.cmake file includes these lines:

set_target_properties(hidapi::include PROPERTIES
  INTERFACE_INCLUDE_DIRECTORIES "/hidapi"
)

Note that installation prefix is missing here from the INTERFACE_INCLUDE_DIRECTORIES path.
In consequence, CMake outputs the following error when I try to consume the hidapi::hidapi target from another project:

CMake Error in CMakeLists.txt:
  Imported target "hidapi::hidapi" includes non-existent path

    "/hidapi"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.

[stsichler]

Reason found:
src/CMakeLists.txt uses CMAKE_INSTALL_INCLUDEDIR for definition of target include directories of hidapi_include before it is defined by GNUInstallDirs:

hidapi/src/CMakeLists.txt

Line 77 in 2b70208

"$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/hidapi>"

See this patch moving GNUInstallDirs to an earlier position solving the problem.

Btw. Note that this problem only occurs at the first cmake configure call, because the CMAKE_INSTALL_INCLUDEDIR will be written into the cmake cache.

[Youw]

Interesting fact: CMAKE_INSTALL_INCLUDEDIR is empty only during the initial CMake run.
That's probably why I didn't catch it myself - I usually run cmake many times while I test anything locally.
Definitely need a good CI check for that.